Electric circuit breaker



Patented Feb. 3, 1953 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT BREAKER Eric Axel Ericson, Plainville, Conn, assigner, by

mesne assignments, to General Electric Company, a corporation of New York Application November 18, 1949, Serial No. 128,172

2 Claims. 1

My invention relates particularly to relatively small so-called air circuit breakers.

One object is to provide a circuit breaker of the manually actuated and automatic type which is compact, efricient and reliable.

It is well known to those familiar with the use and testing of small air circuit breakers that excessive currents frequently encountered have a destructive efiect on parts or" the breaker. The contacts and contact carrying parts frequently have a certain amount of metal melted away, which is either ejected through the arc chute or condensed on the interior of the case where it adversely aiiects the insulating properties of the case. These properties are usually still further deteriorated by a deposit formed as a result of the burning of the housing material in the vicinity of the arc. In addition, small particles of metals which have been thrown off the metallic parts exposed to the arc are impinged on other parts of the breaker, with the possibility that they might interfere with the operation of the breaker. In many cases the effect of the damage to the parts is to increase the time necessary for the breaker to trip or even prevent it from tripping, with the result that the breakerwould not give the protection for which it was designed and it continued in service might permitextensive damage to wiring or equipment.

In any case the effect of interrupting suchexcessive currents is to increase the possibility of subsequent breakdown within the breaker and a consequent danger to personnel.

One object of the invention, therefore, is to prevent reclosing of the circuit through a damage breaker.

Another object is to provide for mechanism by which the circuit can be cpenedforcibly by hand operation in case the movable contact or its carrier fails to snap open.

Another object is to protect the mechanism from damage due to arcing.

Another object is to provide a breaker which is durable and yet which will give an indication of its condition in case it deteriorates.

Fig. 1 is a side View showing the inside of the housing with the switch mechanism in the manually opened circuit or Ofi position in full lines and showing in dotted lines the position of the parts when the circuit is closed.

Fig. 2 is a similar View but partially broken away showing in full lines the mechanism in the position when the circuit has been broken automatically and in dotted lines the closed circuit position.

Fig. 3 is a cross-sectional view taken on the plane of the line 3-3 of Fig. 1.

Fig. l is a cross-sectional View taken on the plane of the line 44 of Fig. 1.

Fig. 4a is a view of a fragment of a detail of the actuating mechanism.

The switch parts are enclosed in an insulating housing having two molded parts 8, 8 held together by screws or rivets Q, 9, d. One circuit terminal iii, usually the line terminal, is held in place in grooves It in the housing and has a stationary switch contact H. The other circuit erminal i2 is similarly mounted and anchored by a screw 2. The inner U-shaped end ll? of the terminal it supports a thermostatic bimetal strip it which is connected by a flexible conductor !5 to the switch contact member it. The latter is pivoted at E7 in a tripping irame member [8 which is pivoted at E9 in the housing.

As shown in Fig. l, the end of the strip [4 is secured to the inside of the looped end 13. This is accomplished by assembling the terminal conductor and the strip with the strip inside the loop and inserting a securing tool through the cutaway portion of the terminal conductor.

The actuating lever 28 is pivoted at 2! in the walls of the housing and has a frame 22 with lugs 22 which overlap the edges of the tripping frame to enable th lever to reset the tripping frame after an automatic release. A spring 23 is under tension between the anchor 24 of the actuating lever and a point 25 intermediate the ends of the switch member it.

In the open circuit position, the switch member 16 presses against the shoulder It of the housing and the tripping lever presses against shoulder 28' when released as in Fig. 2.

The field piece 26 of a magnet is mounted on the bimetal strip M and has an armature 21 which is pivoted at 2B in the housing walls. This armature has a latch member 27 with which the tip of the tripping frame is engages in the normal ready position (Fig. 1).

The spring zepresses the armature clockwise toward the tripping member and the armature in turn presses against the bimetal strip at 3,3. An insulating strip 3! serves as an abutment for spring 2d and is interposed between the spring and the joint in the housing adjacent the-connector rivet 9. Calibration is effected by .adjustment of the screw 32.

Manual operation of the switch by the lever 28 is efiected by moving the lever from one side to the other when the spring 23 provides the snap actionof switch member 16 in the usual manner.

5 6 metal strip and a calibrating screw threaded UNITED STATES PATENTS through the first-named arm of said. L-shaped Number Name Date terminal member below its cutaway portion and 1 809 275 Jennings June 9 1931 extending into the space in said U-shaped por- 2184372 Von Hoom Dec 1939 tion and contacting said bimetal strip at its 5 2'274159 Platz 24 1942 point of securement to the arm of the L-shaped 2:360:682 Hum; Oct 1944 termmal- 2,363,606 Maseng Nov. 23, 1944 ERIC AXE-L 2,371,738 Christofierson Mar. 20, 1945 2,416,164 Ellis et a1 Feb. 18, 1947 REFERENCES CITED 10 2,429,722 Jennings Oct. 28, 1947 The following references are of record in the file of this patent:

Feb. 3, 1953 N. J. SMITH 2,627,555

THERMOSTATIC swrrca Filed Oct. 11, 1949 2 SHEETS-SHEET 1 i h m H wMN 

